Weathering of building materials

Outdoor monuments and building envelopes are built with materials resistant to weather injuries, at least for reasonably long periods. However, their vulnerability is exacerbated by specific atmo- spheric factors that may accelerate deterioration, causing character- istic forms of decay. Weathering is due to a number of atmospheric agents, often in synergism with atmospheric pollutants. Weather and pollution act on various scales, depending on their nature, and their action may be enhanced or attenuated in the proximity of build- ing surfaces. Especially, the microscale interaction that occurs at the interface between the material surface and the free air is crucial. It explains the various deterioration patterns that may be visible on dif- ferent places of the same building.